Oxidized &#34;hydroformed solvent&#34;



lls tented Jan. 26, 1937 m'rso STATES PATENT OFFlCE ard Oil Developmentof Delaware No Drawing. Application 610,

No. 9 Claims.

This invention relates to a new method for the .preparation of improvedsolvents and more particularly to the preparation of liquid productssuitable for use in surface coating compositions to replace aromatic oroxygenated solvents, diluents and drying oils, such as the coal tarsolvents, turpentine and the like. These liquid products are prepared bythe limited oxidationof "hydroformed solvents" and will be calledoxidized hydroformed solvents for the purpose of this invention.

In the appended claims the expression hydroformed solvents is intendedto mean those disclosed in the co-pending application Serial Number583,703, filed December 29, 1931, by Robert T. Haslam, and describedherebelow.

. These hydroformed solvents may be produced from hydrocarbon oildistillates such as burning oil and gas oil and in general fromhydrocarbon m oils of a boiling range including that of gasoline andextending up to about 343 to- 371 C. or somewhat higher. In thepreferred destructive hydrogenation process these distillate oils arepassed in vapor phase with free hydrogen over suitable catalysts at apressure in excess of 20 atmospheres and preferably 50 to 200atmospheres or higher and at a temperature above about 482 C. andpreferably within the range of about 499 to 565. C. with'a suitablepartial pressure of hydrogen and time of contact to secure "adestructive hydrogenation without the formation of appreciable amountsof polymerized or coky material. The amount of hydrogen supplied ispreferably within the range of about 1,000

to 4,000 cubic feet per barrel of feed oil, the amount generallydepending upon the gravity and boiling range of the charging stock. Agreater proportion of hydrogen may be used with suitable-variation infeed rate. temperature and pressure as is known in the art. The feedrate depends upon the reaction temperature, and other operatingconditions such as the partial pressure of hydrogen and may be suitablyabout 1.5 to 4 volumes of oil'per volume of catalyst filled reactionspace per hour. The catalysts preferably comprise the oxides or sulfidesof the metals of Group VI of elements with suitable promoters consistingof the alkaline earth or earth metal oxides. Such catalysts areinsensitive to sulfur poisoning and are suitably classified assulfsctive.

The product of such a vapor phase destructive hydrogenation of petroleumdistiilates and fractions thereod or hydroforming process is called a"hydroformed naphtha for the purpose of this Company, a corporation May10, 1932, Serial" 498 invention and the claims. It possesses highlydesirable solvent properties throughout its boiling range. Fractions ofcomparative volatility prepared from these hydroformed hydrocarbondistillates may be generally used as solvents whereever aromatichydrocarbon solvents such as benzene, toluene, xylene, turpentine oilsand the like are suitable.

The solvent power of the hydroformed solvents depends not only upon theoperating conditions used in the destructive hydrogenation process butalso to some extent upon the source of the hydrocarbon oils used as feedstocks. Operating conditions in the destructive hydrogenation processbeing equal, hydroformed solvents produced from California crudespossess higher solvent power for oxygen-containing compounds, such aspyroxylin or kauri gum, than corresponding solvents from Mid-continentcrudes, while solvents from naphthenic base crudes possess even highersolvent power. Recycled stock from cracking of gas oils, especially suchoils from asphaltic or naphthenic base crudes. form very desirable feedstocks. Extraction products such as those produced in refining oils withsolvents having a selective solvent action for non-paraflinichydrocarbonssuch as phenol or liquid sulfur dioxide, may also be used toadvantage as feed stocks forthe destructive hydrogenation process, andsolvents superior even to pure aromatic hydrocarbons such as toluene andxylene may thereby be produced. Hydroformed solvents prepared bydestructive vapor phase hydrogenation under the operating conditionsdefined above, are far superior to the corresponding straight run orcracked naphthas from the same crudes. In addition to possessingsuperior solvent power, the hydroformed naphthas are hydrunsulfed, i. e.freed from hydrogen sulfide, during the destructive hydrogenationprocess and the sulfur content of even high sulfur oils is reduced belowthat at which bad effects on lead pigments, and the like, are noticed.

It has now been found that if these hydroformed solvents are subjectedto a limited oxidation treatment the resulting product possessesimproved solvent properties above those shown by the hydroformed solventused. The solvent power of the oxidized product is increased withrespect to the dimethyl sulfate, kauri-butanol and aniline point testsand to the various gums, resins. cellulose plastics and the like used inpreparing paints, varnishes and lacquers. In addition the oxidizedproducts may possess desirable drying oil properties comparable toturpentine.

This invention will be fully understood from the following examples:

Example 1 'A cracked hydrocarbon distillate of 378 A. P. I. and boilingbetween the approximate limits of 224 and 332 C. is obtained from aMid-Continent crude." This" distillate contains 0.179% sulfur and hasananiline point of 70 C. It is destructively hydrogenatedover asulfactive catalyst at a pressure of 3,000 pounds per square inch and anaverage catalyst temperature of 510 C. A fraction of the destructivelyhydrogenated product having an end point of 200 C. is removed from theprocess and the higherboiling fractions are continuously recycled. 'Theratio of hydrogen to oil in thefeed to the system is 2200 cubic feet ofhydrogen. per 42-gallon barrel of oil. A portion of the hydroformedsolvent thus produced is placed in a glass-lined bomb and held under 110pounds pressure of air at C. for 48 hours. A description of thehydroformed solvent andthe oxidized product is given in the table below.

Since in the oxidation process some oxygenated products are formed whichhave somewhat higher boiling points than ,the original hydroformedsolvent, it may be desirable for certain solvent purposes to remove thehigher boiling fractions from the product. This is illustrated in thefollowing example.

Example 2 The oxygenated product from Example 1 was distilled and thefraction having the same end point (about 198 C.) as the originalhydroformed solvent was separately collected. The solvent properties ofthis fraction are presented in.the table below.

oxygenated products of a desired volatility and boiling range may alsobe obtained by choosin a suitable hydroformed solvent fraction ofsomewhat lower flnal boiling point, as indicated in the followingexample.

Example 3 A fraction of the hydroformed solvent boiling between theapproximate limits of 77 and 149 C. was subjected to the-oxidationconditions described in Example 1. The resulting oxidized product boiledbetween the approximate limits of 65 and 199 C. The solvent power of thefeed stock and product of this experiment are also shown in the tablebelow:

Solvent power of hydroformed solvents before and after oxidation It isreadily seen from the above examples that the solvent power of petroleumnaphtha-s already greatly increased by hydroformation may be evenfurther increased by oxidation under suitable conditions. *1

The oxidation process is preferably conducted at low temperaturesinsufiicient to cause appreciable decomposition and/or polymerization ofthe hydroformed solvent or the oxidized products. The reactiontemperature depends on other conditions attending the oxidation such asthe pressure, oxygen concentration, time and method of contact, activityof catalysts", if used, and other conditions. Especially desirableproducts are obtained at temperatures below about 300 C. andtemperatures below 150 or even 100 C. may be used withsuitably increasedtime of contact. Free oxygen may be used as the oxidant but an oxidizinggas containing nitrogen or other inert dlluents is preferred. Reactionpressures of about 50 to 200 pounds per square inch are desirablealthough higher pressures up to 100 to 300 atmospheres or more may beused, especially in the lower reaction temperature range between about20 and 120 C. The reaction is preferably conducted under suitableconditions of temperature and pressure so that at least a portion of thehydroformed solvent is in liquid phase. The oxidation may be conductedas either abatch or a continuous process or an oxidizing gas may bepassed through a body of liquid hydroformed solvent maintained atsuitable reaction conditions. Although catalysts are not necessary,their presenceis desirable in order to shorten the time required for theoxidation. This may be accomplished by the addition of oxidationaccelerators, among which may be mentioned copper, cobalt, lead,manganese and their salts. Anti-acids may also be used to advantage.These are basic substances such as metallic oxides or hydroxides orother basic compounds capable of forming salts stable under theoperating conditions with acidic products formed in the oxidationprocess. Calcium hydroxide or oxide is an especially desirableanti-acid.

The product obtained upon oxidation of the hydroformed solvent isnormally. satisfactory as regards color and odor and requires no furtherrefining. The oxidized hydroformed solvent possesses improved solventcharacteristics throughout its boiling range. Fractions of any desiredvolatility may be prepared either by selecting as an oxidation feedstock a hydroformed solvent cut of suitable boiling range or bydistillation of the oxidized product. -The oxidized product if notdistilled contains oxidation products which form resins during thedrying of the solvent and contribute to the strength of the film insurface coating compositions in which they may be employed. The oxidizedhydroformed solvents, particularly prior to distillation, may thereforebe likened to and used in substitution for turpentine and other dryingoils. 7

Fractions of substantially any desired-boiling range may be preparedaccording to the above described methods and maybe used in varioussurface coating compositions accordingto the volatility requirements ofsuch compositions as may be readily determined by one-skilled in theart. The oxidized products are also. suitable 1'or use as rubbersolvents and-for many other solvent purposes. They also possess.superior antidetonating characteristics -;rendering them valuable foruse as motor fuels. Amongthe frac tions which may be prepared for. useinsurface coating compositions and for other purposes may be mentionedthose of the following. approximate boiling ranges: 60 to C., 77. to 121C., 88 to 138 (2., 138 to 188 C., 149- to 171 C.,

171' to-215' C., and others. These fractions are generally characterizedby dimethyl sulfate values above 20 or 40 and kauri butanol values of 40to 1'75 or even higher.

The oxidized hydroformed solvents may be used generally in vehicles forresins, varnish gums and nitrocellulose in varnish, lacquer and paintformulae wherever benzine, toluene, xylene, turpentine and the like aresuitable, and they may be substituted either partially or entirely forsuch hydrocarbons. These solvents may accordingly be used in varnishpreparationsgenerally, in admixture with other suitable solvents for thegums and resins customarily used. They may also be used in lacquerpreparations in admixture with lacquer vehicles generally, such as thosecontaining aliphatic alcohols, ketones, and fatty acid esters and areespecially desirable when used with secondary amyl, secondary butyl andisopropyl alcohols and their acetic esters. Pyroxlin and the othercellulose plastics, plasticizers, gums and resins, such as the phthalicacid glyceride resins, dammar gums and others commonly known to thelacquer industry may be used with these vehicles in making lacquercompositions. These solvents may also be used in homogeneous vehiclescontaining drying oils suitable for admixture with pigments for .thepreparation of paint.

They are also suitable for use in the preparation of quick dryingenamels, such as those containing synthetic resins.

This invention is not to be confused with previously described methodsfor producing oxidized products by the limited oxidation of ordinarypetroleum naphthas, that is naphthas not produced by the hydroformingprocess, since such naphthas are either very resistant to oxidation orelse yield gummy discolored malodorous products on oxidation. For thisreason it has heretofore been considered desirable to render theoxidation stock as highly parafinic as possible prior to its oxidation.This has been accomplished by suitable refining methods, such asacidtreating, to remove aromatic and olefinic compounds or byhydrogenation at low temperatures and pressures with a process similarto that used for hardening fats by which the undesirable compounds aresaturated with hydrogen. Both of these refining processes render thenaphtha suitable for oxida tion only at the expense of a decrease in itssolvent power. The oxidation of such refined naphthas is very diiflcult,and products inferior in solvent power to my improved products aresecured. On the other hand, the hydroformlng process provides highlysuitable oxidation stocks whichpossess greatly improved solventcharacteristics over the original naphthas and render the oxidizedproduct of still greater value as a solvent.

This invention is not to be limited to any examples which are givenherein solely for purpose of illustration nor to any theory regarding,the solvent characteristics of these improved products but. only to thefollowing claims in which I wish to claim all novelty insofar as theprior art per- I mits.

Iclaim:

1. The process of preparing solvents which comprises subjecting a"hydroformed solvent prepared by destructive hydrogenation ofhydrocarbon oils of a boiling range including that of oxidation iseffected at a temperature below about 3. Process according tov claim 1,in which the hydroformed solvent to be oxidized is prepared bydestructive hydrogenation of liquid hydrocarbon extracts obtained bytreating oils with solvents having a selective solvent action fornonparaflinic hydrocarbons.

4. Process according to claim 1 in which an oxidized hydroformedsolvent" boiling below about 232 'C. is secured by distillation of theproduct of the limited oxidation treatment.

'5. Process according to claim 1 in which an oxidized hydroformedsolvent boiling substantially below about 232 C. and possessing dryingoil properties is secured by subjecting a hydroformed solvent boilingbelow about 230' C. to the limited oxidation treatment and subsequentdistillation.

6. Process according to claim 1 in which the oxidation is conducted withair and with a hydroformed solven substantially in liquid phase.

7. Process according to claim 1 in which the limited oxidation isconducted with air at a pressure above about 200 pounds per square inchand at a temperature below about 120 C.

8. Process according to claim 1 in which the limited oxidation isconducted with the hydroformed solvent substantially in liquid phasewith air at a pressure above about 50 pounds per square inch and at areaction temperature below about 150 C.

9. An oxygen-containing organic solvent derived i'rom a hydrotormedsolvent having a kauri butanol solvent value substantially above 40 anda dimethyl sulfate value above 20.

CARL WINNING.

